1. Field of the Invention
The present invention relates to an airbag apparatus comprising an airbag which is attached to a housing part of a vehicle. Specifically, the present invention relates to a head protecting airbag which is configured so as to be folded up to be housed at an upper part of a window of the vehicle in a state that the periphery of the airbag is covered by a protecting cover of a synthetic resin after folded up so as to deploy and inflate to protrude downward from the housing part to cover an interior side of the window when an inflating gas is introduced thereinto.
2. Related Art
Conventionally, a head protecting airbag which completes its inflation so as to cover an interior side of a window of a vehicle is made to comprise a gas introducing portion which inflates so as to separate an interior wall portion and an exterior wall portion from each other by allowing an inflating gas to be introduced thereinto and a non-introducing portion which keeps the interior and exterior wall portions joined to each other so as not to allow the inflating gas to be introduced thereinto (for example, refer to Japanese Patent Publication No. JP-A-2004-203234).
Then, the gas introducing portion comprises a gas supply passage portion and a plurality of parallel cells. The gas supply passage portion is disposed so as to extend along the longitudinal direction at an upper edge of the airbag and is made to communicate with a connecting port portion which connects to an inflator for supplying the inflating gas. The parallel cells are arranged in parallel in the longitudinal direction in a protecting area of the airbag which protects an occupant and are each formed so as to have an inflating gas inlet port at an upper portion thereof which faces the gas supply passage portion and to extend to a lower edge of the airbag.
These parallel cells are provided so as not only to control the shape of the airbag which has completed the inflation so that the airbag is not inflated spherically but into a plate-like shape by restricting the inflation in a thickness direction but also to generate a tension at the lower edge of the airbag along the longitudinal direction by narrowing the breadth of the airbag in the longitudinal direction so as to restrain the movement of the airbag to the outside of the vehicle even when the cells are brought into interference with the occupant to thereby increase the occupant restraining performance by the airbag.
In addition, the non-introducing portion of the airbag includes a peripheral portion which defines an outer peripheral edge of the airbag and extending partitioning portions which extend upward continuously from a lower edge portion of the peripheral portion which locates at from the lower edge of the airbag so as to partition the parallel cells.
In the conventional head protecting airbag, however, the number of parallel cells arranged in parallel with each other in the longitudinal direction have openings simply disposed open at upper ends thereof to thereby be made to communicate with the interior of the gas supply passage portion.
By this structure, when the inflating gas is introduced into the gas supply passage portion from the connecting port portion to thereby flow from the upstream side to the downstream side along the longitudinal direction within the gas supply passage portion, the inflating gas tends to easily flow linearly, and as a result, the parallel cell at the downstream end deploys most quickly to inflate thick with ease, or the parallel cell which is closest to the connecting port portion tends to deploy quickly to inflate thick with ease.
Namely, with the conventional head protecting airbag, there has been a problem with making the predetermined parallel cell between the upstream side and the downstream side of the gas in the gas supply passage portion is deployed quickly and inflated thick.
Further, as a head protecting airbag apparatus, there has been an airbag apparatus in which a folded airbag is housed at an upper part of a window as a housing part within a compartment of a vehicle in a state that the periphery of the folded airbag is covered by a cover made of a synthetic resin (for example, refer to JP-A-2002-249015 (FIGS. 9 to 14)).
In the above conventional head protecting airbag apparatus, however, the cover that covers the folded airbag is such as to cover the overall periphery of the folded airbag so as to prevent the collapse of the folded airbag from the folded state. Then, an attachment piece portion which attaches the airbag to the housing part side is passed through the cover, and the cover is integrated with the airbag in such a state.
On the other hand, in a conventional airbag apparatus including an airbag and an inflator which is adapted to be installed on a vehicle, the airbag has a cylindrical connecting port portion which introduces an inflating gas from the inflator into the airbag (refer to, for example, JP-A-2003-11768).
Then, this connecting port portion is externally installed on the inflator and is connected to the inflator by being fastened by a clamp.
However, with the connecting construction between the connecting port portion and the inflator by making use of only the clamp, in case the output of the inflator increases as the volume of the airbag increases, there is caused a risk that the connecting port portion is dislodged from the inflator when the inflator is activated, and there still remains a room for improvement in increasing the connection strength.